• Question: Why do carcinogenic compounds such as benzene cause cancer.

    Asked by 538catf38 to John, Laura, Luke on 23 Jun 2016.
    • Photo: Laura Finney

      Laura Finney answered on 23 Jun 2016:

      Some things cause cancer for slightly different reasons, but basically carcinogens cause changes to your DNA so it mutates. Some carcinogens don’t do this but make your cells replicate very fast meaning it increases the chance of DNA changing somewhere along the lines. Basically it causes the cells not to know when to stop replicating and so they just keep going. Usually when you cut yourself and you heal, when your cells eventually touch again they know the hole is now closed and to stop, but cancerous cells don’t know to do this anymore, so they keep going. That’s how a tumour is formed and how carcinogens work.

    • Photo: Luke Williams

      Luke Williams answered on 23 Jun 2016:

      Laura is bang on – but I will go into detail with regards to benzene.

      Benzene, and a number of hydrocarbons, present a bit of a problem for the body. They aren’t particularly soluble, and they don’t really do much. But the body doesn’t want them there, so has to find some way to get rid of them.

      Benzene itself isn’t a huge issue, it is what it gets converted into that really gets problematic. Benzene gets converted into a number of things including benzene oxide and a number of alcohols, most notably phenol, catechol and 1,2,4-benzenetriol. These metabolites end up in the bone marrow as well as elsewhere (e.g. liver) and inhibit some key enzymes involved in the repair of DNA such as topoisomerase II, which are vital to ensure that DNA replication and repair work successfully.

      I believe there is also some issue with the production of benzene based radicals, which cause oxidative damage to DNA (and presumably other things too). A third issue is the metabolites also stick to things such as DNA and other key molecules of cells, causing issues.

      Thus benzene is not actually carcinogenic, its metabolites are. They don’t always cause DNA errors, but they stop the body repairing those errors which it does make. May seem silly, but they are important distinctions.

Comments